1. Field of the Invention
The subject invention generally pertains to series-wound universal motors and more specifically to the electrical terminals of such a motor.
2. Description of Related Art
The universal motor is a single-phase commutated motor with wound field coils in series with a wound rotor armature. Due to their high power-to-weight ratio, universal motors are particularly useful for powering handheld tools and various small household appliances such as vacuum cleaners. Since handheld tools and small appliances are often portable, they may be subject to jarring, vibration and mechanical shock, thus their motors should be designed to withstand such handling. Moreover, small tools and appliances are often mass-produced, so their motors need to be quick and easy to assemble.
The current inventor, Dennis Mancl, discloses a good example of a mass-produced universal motor in U.S. Pat. No. 5,465,016; which is specifically incorporated by reference herein. The patented motor includes several motor terminal assemblies that serve the purpose of wiring the shunts, which extend from the commutator brushes.
A drawback of the patented design, however, is that each terminal assembly for the shunts includes at least two parts, a nylon terminal pocket and a SIAMEZE terminal (SIAMEZE is a trademark of Tyco Electronics Corporation of Bermuda with an Tyco Electronics business segment in Harrisburg, Pa.), and these terminal assemblies are actually subassemblies, which in turn are attached to the motor in some manner, thereby creating yet another assembly. The multiple parts and assemblies can increase the motor's cost and perhaps decrease its ability to withstand shock and vibration.
Moreover, the SIMAMEZE terminals disclosed in the '016 patent by Mancl are used for wiring shunts, which are stranded wires. Since stranded wire is typically comprised of relatively delicate strands, wire-pinching SIMAMEZE terminals can possibly damage such strands, thus SIMAMEZE terminals are arguably more suited for solid wires than for the stranded shunts of commutator brushes.
Consequently, a need exists for a robust universal motor that is quick and easy to assemble.